1. Field of the Invention
This invention relates to a car power source apparatus that is provided with a circuit to detect battery voltage of a plurality of series-connected batteries in a battery array.
2. Description of the Related Art
For an on-board power source apparatus that drives a car, it is necessary to raise output voltage to increase output power. This is because output power is proportional to the product of battery voltage and current. For example, output voltage for a power source apparatus that drives a hybrid car or electric automobile is extremely high at 200V or more. A high voltage power source apparatus has many rechargeable batteries connected in series to form a battery array.
In a battery array with many batteries connected in series, it is important to charge and discharge those batteries while preventing over-charge and over-discharge of each battery. This is because over-charge and over-discharge degrade battery electrical performance as well as shorten battery lifetime. A power source apparatus that detects battery voltage and controls battery charging and discharging to prevent over-charge and over-discharge has been developed (refer to Japanese Patent Application Disclosure 2002-199510).